Textile-treating resins, typically aminoplast-forming substances, such as N-methylol monomeric and polymeric compounds, such as urea-formaldehyde resins, have been widely employed in the treatment of textile fabrics, particularly rayon, cotton and blends therewith, with noncellulosic textiles, such as polyesters, to impart permanent-press, such as wrinkle-resistant, crease- and shape-retentive, properties and other desirable properties to the treated fabric. One process of treating the textile material comprises: impregnating the material with an aqueous solution of the aminoplast-forming substances, such as by immersion in a textile-treating bath; drying the treated material to a precured or sensitized state; and, thereafter, either before or after the fabrication of the treated fabric in its sensitized state into a finished garment, curing the aminoplast-forming substances on the treated material. Thus, in one process known as the precure process, the textile fabric is treated, resinated and cured, and the garment then is fabricated, while in the post-cure process, the textile fabric is treated, dried, fabricated into a garment and then cured. Optionally, the treated material, either after the precuring or sensitizing and drying steps or after the curing step, may be treated further to impart other desirable properties, or, in one embodiment, to remove any free formaldehyde from the treated fabric.
One serious problem associated with such treatment of textile fabric concerns the presence of free formaldehyde on the treated textile fabrics and finished garments, as well as either after such treatment or after storage of the treated fabrics or finished garments. The presence of free formaldehyde on the fabrics, or derived from the storage of the fabrics under humid conditions, arises from the employment of the N-methylol monomeric compounds used in the treating process. The presence of free formaldehyde is objectionable not only due to its odor and the retention of the odor, particularly in garment-handling and fabrication areas of the plant, and more particularly in air-conditioned plants, but also due to the possibility of allergenic and irritating reactions to those people in the chemical-treating area or those who handle or wear such garments containing such treated fabrics. The problems associated with free formaldehyde on treated textile fabrics are well known, and have been the object of considerable efforts to produce formaldehyde-free textile fabrics, or, at the very least, to produce textile fabrics having a reduced free formaldehyde thereon.
Historically, urea and other urea compounds, such as the cyclic ethylene and propylene urea, have been employed as scavengers for free formaldehyde in the textile-furnishing field, in order to reduce substantially the free formaldehyde, and, therefore, diminish the formaldehyde odor associated with the treated textile material (see, for example, U.S. Pat. No. 3,590,100, hereby incorporated by reference). However, the use of urea is not wholly satisfactory in that the textile retains undesirable odors, and, in addition, the use of excess urea tends to alter the buffered cure of the fabric and to alter the textile properties of the treated fabric, such as the hand properties. In addition, the free-formaldehyde content of the aminoplast used in the textile-treating bath has been reduced in a separate operation also by removal of the free formaldehyde by reaction with phthalimide to form an insoluble adduct with the free formaldehyde, which adduct may be separated from the aminoplast-treating solution before treatment of the fabric (see U.S. Pat. No. 3,723,058, hereby incorporated by reference).
Another technique provides for a process for scavenging free formaldehyde, wherein the cellulosic textile material, after having been impregnated with a solution of an aminoplast-forming substance and dried, is sprayed or padded with a solution of urea or another formaldehyde acceptor (see U.S. Pat. No. 3,957,431, hereby incorporated by reference). Urea is stated as the preferred compound suitable for use in the process, but other five-membered, carbonyl-containing, heterocyclic, nitrogen-containing ring compounds are also stated as being effective formaldehyde scavengers in the post-treatment of the treated textile fabric. Such cyclic compounds include the cyclic urea compounds, wherein the imide nitrogen reacts particularly rapidly with the free formaldehyde. In this process, the spraying or padding of the treated textile material with the formaldehyde-acceptor solution is carried out after drying, and in the post-cure process.
U.S. Pat. No. 3,749,751 discloses the use of an amide or pyrrolidone-type compound for reduction of formaldehyde in coating solutions containing methylated carbamates. U.S. Pat. No. 3,723,377 discloses the use of 4,5-dihydroxy-2-imidazolinone (DHEU) and its derivatives to reduce formaldehyde or aqueous mixtures containing carbamates for coating. U.S. Pat. No. 3,597,380 teaches the use of melamine with solutions of methylated carbamates having free formaldehyde to reduce the free-formaldehyde content.
The problems associated with formaldehyde in textile-finishing solutions employed in the recent past are set forth and are described in "Formaldehyde and Textile Finishing", Bille and Petersen, Melliand Textilberichte, February 1976 (hereby incorporated by reference).
Although past processes have been effective in some regard in reducing free formaldehyde, such processes have not proven wholly satisfactory. For example, the use of urea or ethylene urea is unsatisfactory, due to the requirement for a high concentration to effect substantial reductions and the associated changes occasioned by such high concentration, and the effect on light fasteners, when ethylene urea is employed. The requirement for special pretreatment for the separation of an insoluble adduct, as when phthalimides are employed, to scavenge formaldehyde is also undesirable. In addition, other processes require separate spraying and padding treatments and additional drying, which add to the cost and expense of such processes.
Therefore, there is a need for a process to provide for the reduction of free formaldehyde in cellulosic-containing articles, particularly treated textile fabrics, which process would provide for the reduction of formaldehyde to low, acceptable and tolerable limits by the use of only small quantities of materials in a simple process, such as low quantities of additive materials in the textile-treating bath, and the use of materials which avoid undesirable alterations in the article so treated.